Nuclear Chemistry
Why do transmutations occur?
Because nucleus of the atom wants to become stable!!!
Beta Decay
Beta particles β: electrons ejected from the nucleus when neutrons decay ( n -> p+ +β- ) Beta particles have the same charge and mass as "normal" electrons.
What's a positron?
A positron is identical to an electron, except that it has a positive charge This is a particle with no mass yet positively charged.
Gamma Rays
Almost all nuclear decay also releases some energy in the form of gamma rays Gamma rays similar to X-Rays, but have more energy.
radioactive elements
The ratio in all nuclei of elements with atomic numbers greater than 83 makes them unstable. Most nuclei are stable The ratio of protons to neutrons determines the stability
half life
The time it takes for half of the atoms in a given sample of an element to decay
Nuclear Reactions and Energy
The total mass of a nucleus is less than the sum of the masses of the individual protons and neutrons. The matter that has been converted into energy is known as the mass defect. Turns out (in the unusual case of a nuclear reaction) mass can be converted to energy E = mc2
What stops gamma particles?
They have no mass. Gamma radiation has no charge. Most Penetrating, can be stopped by 1m thick concrete or a several cm thick sheet of lead.
radioisotope used in geological formations
U-238
C-14
Used in detecting the age of once living organisms (fossils)
I-131
Used in detecting thyroid cancer
U-238
Used in geological formation and age of rocks
Transmutation
When the nucleus of one element is changed into the nucleus of a different element.
When a nucleus decays, it emits radiation in the form of
alpha particles beta particles gamma particles
Which emission causes the atomic number of a nuclide to decrease by 2 and its mass number to decrease by 4?
an alpha particle
Which particle has the greatest mass
an alpha particle
Which particle has the least mass?
beta particle
What stops alpha particles?
can be stopped by a sheet of paper, clothing.
Which radioisotope is used to determine age of once living organisms?
carbon-14
Fission Reactions
high energy particle (usually a neutron) is captured by a nucleus, causing it to go unstable, and split. When the nucleus splits, a lot of energy is released. products are highly radioactive
chemical reactions
involve exchange or sharing of electrons
Nuclear chemistry
involves changes in the nucleus of an atom
An unstable nucleus spontaneously releases a positron. This is an example of
radioactive decay
environment radioactive risk factor
radioisotopes with long half lives
An unstable nucleus
spontaneously decays, forming products that are more stable.
spontaneous decay
the release of alpha, beta, positrons and/or gamma radiation from the nucleus of an unstable isotope
Artificial transmutation capture
when element is made radioactive by bombarding its nucleus with high energy particles.
main risk of radioactive powerplant
workers being exposed to radiation
What stops beta particles?
Can be stopped by aluminum foil or a block of wood.
Co-60
Cancer treatment, tracing
Radioisotope dangers
Damage to healthy tissue, Mutations - transferred to next generations Waste material with a long half life. Accidents.
Alpha decay
Emission of alpha particles a Helium nuclei two protons and two neutrons charge +2( quantity and quality?) can travel a few inches through air
Radioisotopes
For any element, an isotope that is unstable (and thus radioactive) is called a radioscope.
Gamma Decay
Gamma radiation γ : electromagnetic energy that is released. Gamma rays are electromagnetic waves.
Radioisotope Applications
Have applications in industry, medicine and research. Also source of energy with a little raw material.
Fusion Reactions
Involve the combining of light nuclei to form heavier ones. Require extremely high temperatures and pressures Major advantage - products are not highly radioactive
Balancing Nuclear equations
Label all components of the equation. You can use X for the unknown Balance charges ( bottom numbers) Balance mass ( top number ) Make sure that numbers left and right of an arrow are equal. Find a missing element.
when would it be a fission reaction?
The nuclear equation would be a fission reaction when there are larger compounds being the heavy nuclei are being converted into lighter nuclei.
the mass defect
The matter that has been converted into energy
Natural transmutation Decay
Radioactive element breaks down to simple more stable element
Nuclear decay
Radioactive isotopes changing their atomic structure.